1. in philosophy, the position that reality, including the natural world, is not independent of mind. Positions range from strong forms, holding that mind constitutes the things of reality, to weaker forms, holding that reality is correlated with the workings of the mind. There is also a range of positions as to the nature of mind, from those holding that mind must be conceived of as absolute, universal, and apart from nature itself to those holding that mind may be conceived of as individual minds. See absolute idealism; idealistic monism; subjective idealism. See also mind–body problem.

2. commitment to moral, political, or religious ideals.

3. see Platonic idealism. Compare materialism. —idealist n. —idealistic adj.